Wednesday, April 11, 2012

Using thickeners in our products

I'm afraid I can't find the e-mail/comment I wanted to quote here, but someone noted the other day that their body butter wasn't very thick. I wanted to take this opportunity to remind you that our products may take up to a few days to thicken to their final viscosity and not to panic if you find it isn't thickened the next morning! One of the reasons for this phenomenon? Our fatty acids need time to cool to get to their normal solidification point!

The various emollients we use contain fatty acids, and those fatty acids have different solidification temperatures. Let's say we use something like shea butter with cetyl alcohol in our product. Shea butter contains a number of different fatty acids with different melting points - stearic acid stays solid until about 69.6˚C, palmitic acid at 62.9˚C, oleic acid at 13˚C, and linoleic acid at -5˚C. This means that stearic acid is still going to be liquidy at 70˚C, our heat and hold temperature, but it'll start to solidify when we're still mixing our ingredients. The palmitic acid will start to solidify around 63˚C. The cetyl alcohol will be melty until about 49˚C, and so on. So when our product is in the heat and hold phase, it's not going to be the true thickness of the end product.

Think about coconut oil, which might be listed as being coconut oil 76, which means it melts at 76˚C. In the summer, this stuff turns liquid in my workshop! If you find the product coconut oil 92, it means that the fatty acid profile has been altered to include more fatty acids that have a higher melting point. 

It can take a while for our products to reach their final temperature. If it's the summer and you have a 25˚C workshop, your product might take a really long time to get to what we would consider room temperature of 18˚C to 20˚C. If it's the winter, they might be there before you've finished mixing! This is another reason not to package your products before they reach room temperature - if you aren't sure of their final consistency, how do you know if a pump or a tottle or even a jar might be the best choice? (The first reason is to avoid condensation on cap of your container!)

And note, when you choose another thickener, there will be differences in when that fatty alcohol or fatty acid solidifies. Cetearyl and cetyl alcohol melt around 49˚C, cetyl esters anywhere from 43˚C to 47˚C, and stearic acid around 69˚C. Big differences, eh? And it's noted that cetyl esters can take up to two days to come to the final thickness.

Related post:
Why does my butter go grainy?


Scented13 said...

Hi Susan, not sure if this has been asked and answered before, I have looked but couldn't find anything - Can we thicken our lotions after making them if they haven't thickened up enough? My lotion contains Emulsifyer NF & Cetyl Alcohol but I feel it's too thin and just wondering if there is any remedy to this? Thank you for this AWESOME blog and your wonderful eBooks, I have learnt and continue to learn a great deal of information from you and can't thank you enough for sharing with us!!!

Susan Barclay-Nichols said...

Hi Scented13: I've answered your question in today's Weekend Wonderings. No, you can't re-heat the lotion, but next time, use less water, more thickener, a co-thickener, or a different thickener.